[PATCH net v2] dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state

[PATCH net v2] dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state

[Alexey Kodanev]

ccid2_hc_tx_rto_expire() timer callback always restarts the timer
again and can run indefinitely (unless it is stopped outside), and after
commit 120e9dabaf55 ("dccp: defer ccid_hc_tx_delete() at dismantle time"),
which moved ccid_hc_tx_delete() (also includes sk_stop_timer()) from
dccp_destroy_sock() to sk_destruct(), this started to happen quite often.
The timer prevents releasing the socket, as a result, sk_destruct() won't
be called.

Found with LTP/dccp_ipsec tests running on the bonding device,
which later couldn't be unloaded after the tests were completed:

  unregister_netdevice: waiting for bond0 to become free. Usage count = 148

Fixes: 2a91aa396739 ("[DCCP] CCID2: Initial CCID2 (TCP-Like) implementation")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
---

v2: * corrected bug origin commit id
    * clarified commit message about sk_stop_timer()

 net/dccp/ccids/ccid2.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 1c75cd1..92d016e 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -140,6 +140,9 @@ static void ccid2_hc_tx_rto_expire(struct timer_list *t)
 
 	ccid2_pr_debug("RTO_EXPIRE\n");
 
+	if (sk->sk_state == DCCP_CLOSED)
+		goto out;
+
 	/* back-off timer */
 	hc->tx_rto <<= 1;
 	if (hc->tx_rto > DCCP_RTO_MAX)
-- 
1.7.1

Re: [PATCH net v2] dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state

[Eric Dumazet]

On Fri, 2018-01-26 at 15:14 +0300, Alexey Kodanev wrote:
> ccid2_hc_tx_rto_expire() timer callback always restarts the timer
> again and can run indefinitely (unless it is stopped outside), and after
> commit 120e9dabaf55 ("dccp: defer ccid_hc_tx_delete() at dismantle time"),
> which moved ccid_hc_tx_delete() (also includes sk_stop_timer()) from
> dccp_destroy_sock() to sk_destruct(), this started to happen quite often.
> The timer prevents releasing the socket, as a result, sk_destruct() won't
> be called.
> 
> Found with LTP/dccp_ipsec tests running on the bonding device,
> which later couldn't be unloaded after the tests were completed:
> 
>   unregister_netdevice: waiting for bond0 to become free. Usage count = 148
> 
> Fixes: 2a91aa396739 ("[DCCP] CCID2: Initial CCID2 (TCP-Like) implementation")
> Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
> ---

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks Alexey.

Re: [PATCH net v2] dccp: don't restart ccid2_hc_tx_rto_expire() if sk in closed state

[David Miller]

From: Alexey Kodanev <alexey.kodanev@oracle.com>
Date: Fri, 26 Jan 2018 15:14:16 +0300

> ccid2_hc_tx_rto_expire() timer callback always restarts the timer
> again and can run indefinitely (unless it is stopped outside), and after
> commit 120e9dabaf55 ("dccp: defer ccid_hc_tx_delete() at dismantle time"),
> which moved ccid_hc_tx_delete() (also includes sk_stop_timer()) from
> dccp_destroy_sock() to sk_destruct(), this started to happen quite often.
> The timer prevents releasing the socket, as a result, sk_destruct() won't
> be called.
> 
> Found with LTP/dccp_ipsec tests running on the bonding device,
> which later couldn't be unloaded after the tests were completed:
> 
>   unregister_netdevice: waiting for bond0 to become free. Usage count = 148
> 
> Fixes: 2a91aa396739 ("[DCCP] CCID2: Initial CCID2 (TCP-Like) implementation")
> Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
> ---
> 
> v2: * corrected bug origin commit id
>     * clarified commit message about sk_stop_timer()

Applied and queued up for -stable.